SAO PAULO — Former Brazilian President Luiz Inacio Lula da Silva was found not guilty of obstruction of justice on Thursday, in one of several cases against the jailed politician.

The decision is not entirely surprising since the prosecutors' office had, in the end, asked the judge to acquit da Silva, saying it had not found evidence that the former president was involved in attempts to interfere with a massive corruption investigation involving state-run oil company Petrobras.

The initial indictment accused da Silva and others of trying to buy the silence of a former Petrobras executive who was implicated in the scandal.

But Judge Ricardo Augusto Soares Leite ruled Thursday that the evidence did not present a clear picture of what actually happened. He added that the testimony of witnesses against da Silva, including some cooperating with the state, was not sufficiently credible.

"There are innumerable possibilities and circumstances as to what really happened," Leite wrote.

Da Silva's lawyers welcomed the decision and said that the judge's reasoning in Thursday's ruling could equally be applied to the case in which da Silva was convicted last year.

In that case, da Silva was convicted of trading favors with a construction company also involved the corruption scandal in exchange for the promise of a beachfront apartment.

"It is hoped that justice also prevails in the triplex case to reinstate Lula's full liberty," lawyer Cristiano Zanin Martins said in a statement.

Both cases are part of the Car Wash investigation in which prosecutors allege politicians granted favors and state contracts to companies for bribes and campaign contributions.

Da Silva also faces charges in other pending cases.